There are more and more environments in which it is desirable or necessary to sense data, such as pressure. For example, in automotive applications, it is necessary to sense the pressure of such media as gasoline or transmission oil. Obviously, a sensor must be exposed to these harsh media to produce accurate pressure data.
Contemporary pressure sensors require special protection of the electrical connections on the sensor. Typically, attempts at such protection are made by depositing a gel over the portion of the sensor exposed to the harsh media, thereby sealing the vulnerable electrical connections from the harsh media. If the sensor electrodes were left exposed to the media the electrical connections would soon fail due to the corrosive nature of the media. Depositing the gel on the sensor is ineffective in protecting the electrical connections and, in addition, it is a relatively expensive procedure.
A typical prior art capacitive sensor requires at least some electrical connections to be exposed to the media because of the construction of the sensor. Prior art sensors have a first capacitive electrode that is electrically isolated from a second capacitive electrode such that a sealed cavity is formed between the two electrodes. Thus, a capacitor is formed. The electrode of a prior art sensor that is in contact with the media requires protection from the media such as expensive approach commonly referred to as "oil fill".
What is needed is an improved capacitive pressure sensor that is low-cost and effectively isolates the sensor's electrical connections from the harsh media to which the sensor may be exposed.